Having checked both relays on the multimeter for resistance and continuity I can confirm what pressing the brake light told me with each relay in turn and that was that both relays were kaput.
I bought replacement relays - still no start until I did as Dave suggested and gave the starter a couple of taps with the mallet whilst starter depressed and voila - success. It seems that the problem was a combination of broken relay and stuck solenoid. Many thanks for everybody's help - it's what this site is all about.
Roger, pardon my cyber talk ignorance, I appreciate the email and your help.
